5KeyboardUsed to input text and numbers into the computer
6Mouse Used to guide a pointer or cursor around the screen. Functions are selected with the aid of the control buttonsSome mice have a wheel which is used for zoom and scrolling
7Tracker Ball This device is very similar to a mouse. It is used where there is little desk space available for a mouseThe large ball is on the top of the device and is rotated using the palm of the hand
8Joystick Used commonly for games Used in many simulation situations. E.g. Flight and tank simulators
9Graphics Tablet Used for sketching or tracing drawings into a computer Uses a puck or a pen to detect the exact position of the cursor on a drawing etc.
10Digital Stills CameraThis camera stores the pictures it takes in digital form. These can the be downloaded to a computer for inclusion in a DTP document etc.
11ScannerUsed to electronically convert paper images to to computer files.Text can be scanned in using OCR (Optical Character Recognition) softwareFlat bed ScannerHand held Scanner
13Flatbed Plotter Only used by CAD programs Produces line drawings Page size is limited by size of plotter bedNot suitable for printing pictures
14Drum PlotterDrum plotter are usually used in industry to produce large drawings (up to A0)Paper moves back and forwards while pen moves from side to side
15Fax/Modem A modem is both an input and output device Data can be exchanged with drawing offices across the world electronically
16Storage DevicesA PC usually has several methods of storing data on it. These may include a mixture of fixed and removable storage systems
17Floppy Disc Portable removable storage Only holds 1.44 MB of data Can be used in most computer systemsEasily damaged
18Hard Drive Large capacity storage Not portable – build into base unit of computerFast saving and retrieval of data
19Zip DiscSimilar to floppy disc but greater storage capacity (100 – 250 MB)PortableNot all computers have Zip drives
20CD RomHigh capacity portable storageNeeds a CD writer to store data
21CAD CommandsYou must know for your exam the following common CAD commands
22CAD Commands 1An on screen grid which can be set to any size. Can make it easier to do orthographic drawingsAn on screen grid which is set at 30 deg. Can make it easier to do Isometric drawings
23CAD Commands 2This restricts the start and end points of lines to a predefined gridThis allows different types of information to be keep separate on a drawing
24CAD Commands 3 Allows the drawing of rectangular shapes on screen Allows a user to increase or decrease the screen view so that they can see more detail
25CAD Commands 4Allows the user to copy and position objects or parts of a drawing without having to redraw themAllows the user to draw arcs and circles on screen
26CAD Commands 5 Fillet puts a radius on a corner (rounded) Chamfer puts a 45 deg angle on a cornerThis allows the user to draw circular or rectangular arrangements from a single object
27CAD Commands 6 Trim/Break removes an unwanted section of line, etc. Extend makes a line, etc. longer (usually to meet another object)This allows the user to turn an object at any angle about a point
28CAD Commands 7This allows the user to change the size of an objectThis flips an object about the horizontal or vertical axis
29ADVANTAGES OF A CAG SYSTEM OVER A DRAWING BOARD 1 Storage and retrievalA completed drawing or series of drawings can be stored on hard drive, floppy disc, Zip disc or CD-R. These formats require less storage space than paper drawings. The drawings can then be printed as many times as required with no deterioration in quality.Ease of modificationCompanies who use CAG systems have advantages over competitors who rely on more traditional methods of modifying drawings. The ease and speed with which modifications can be made reduce time and costs, which in turn increases productivity.Repetitive elements (library)Drawings can contain a number of repetitive elements such as doors, windows, kitchen fittings and appliances. It is useful to have these items stored in a CAD library file. CAD library files are available for mechanical engineering, architecture and electronics. Items that you design need only be drawn once, saved to a library file, then retrieved and positioned each time they are required on a drawing. This saves time and effort, which increases productivity.
30ADVANTAGES OF A CAG SYSTEM OVER A DRAWING BOARD 2 Drawing speedIt does take a considerable amount of time and financial investment by companies to train their CAG operators. In relative terms, however, drawing production is much faster using CAG than using traditional methods, so the company will save time and money in the long run.Standardisation of drawingsStandardisation of drawings is often determined by drawing standards such as 851. Standardisation of drawing layouts and styles can easily be created in the 'in-house' or corporate style adopted by the operator or the company.Drawing size and flexibilityDrawings can be enlarged or reduced with no loss of detail. Extremely fine, detailed work can be produced using commands such as ZOOM. Positive location tools such as GRID, GRID SNAP and ATTACH enable accuracy to be maintained even in the smallest details.